A type of battery cell

Abstract

This invention belongs to the field of battery technology, specifically disclosing a battery cell. The cell comprises a cover plate and a housing, forming an accommodating space for mounting electrode arrays. A seam is formed between the circumferential sidewall of the cover plate and the inner wall of the housing. Along a direction perpendicular to the circumferential sidewall of the cover plate, the housing and cover plate are welded together using through-welding to form a first welded portion. Along a direction perpendicular to the plane of the cover plate, the housing and cover plate are welded together at the seam to form a second welded portion, located on the end face of the cover plate away from the electrode arrays. During the formation of the second welded portion, the existing first welded portion at the seam can shield the laser generated during its formation, preventing laser leakage into the accommodating space and damaging the electrode arrays. The use of two welding processes simultaneously ensures high connection strength between the housing and the cover plate, stable and reliable welding quality, and avoids incomplete welding.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a battery cell. Background Technology

[0002] In steel-cased batteries, both the casing and the cover are made of stainless steel, a material with high hardness. Compared to conventional aluminum-cased batteries, it's difficult to machine a step on the inner wall of the casing near the opening to fit the cover. Typically, after the casing and cover are aligned, the seam between them is directly welded. However, due to the lack of a step to support the cover, it's difficult to position the cover, resulting in decreased welding quality and assembly accuracy. Furthermore, without a step to shield the laser, the laser can easily leak in through the seam between the cover and casing, potentially burning the internal electrode assembly and reducing product yield. Summary of the Invention

[0003] The purpose of this invention is to provide a battery cell in which laser leakage is less likely to burn the electrode assembly during the welding of the casing and the cover plate, and the welding quality between the casing and the cover plate is good, the welding yield is high, and the connection is reliable.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] This invention provides a battery cell, comprising:

[0006] A housing, wherein at least one end of the housing is provided with an opening;

[0007] A cover plate is disposed at the opening. The cover plate and the housing together form an accommodating space for installing the electrode assembly. A joint is formed between the circumferential sidewall of the cover plate and the inner wall of the housing. The end face of the cover plate facing away from the electrode assembly is flush with the end face of the housing along a first direction, which is a direction perpendicular to the plane where the cover plate is located.

[0008] Wherein, along the direction perpendicular to the circumferential sidewall of the cover plate, the housing and the cover plate are welded together by through welding to form a first welded part, and the melting direction of the first welded part is perpendicular to the circumferential sidewall of the cover plate; along the direction perpendicular to the plane of the cover plate, the housing and the cover plate are welded together by seam welding at the joint to form a second welded part, and the melting direction of the second welded part is perpendicular to the plane of the cover plate, and the second welded part is located on the end face of the cover plate away from the electrode group.

[0009] Optionally, the wall thickness of the shell is a, and the value of a ranges from 0.1mm to a ≤ 0.3mm.

[0010] Optionally, the thickness of the cover plate is b, and the value of b is in the range of 0.5mm≤b≤1.2mm.

[0011] Optionally, the portion of the first welded part located on the cover plate is the first molten region; along the first direction, the distance between the side of the first molten region near the accommodating space and the end face of the cover plate facing the accommodating space is d;

[0012] The range of values ​​for d is: 0mm < d ≤ 0.3mm.

[0013] Optionally, along the first direction, the distance between the side of the first molten region away from the accommodating space and the end face of the cover plate away from the accommodating space is f;

[0014] The range of values ​​for f is: 0.1mm < f ≤ 2a.

[0015] Optionally, along the first direction, the penetration depth of the second weld on the cover plate and the housing is e;

[0016] The range of values ​​for e is: 0.1mm≤e<f.

[0017] Optionally, the melting depth of the first molten region is c along the direction perpendicular to the circumferential sidewall of the cover plate;

[0018] The value range of c is: 0.1mm≤c≤0.5mm.

[0019] Optionally, two cover plates are provided, and the housing has openings on opposite sides along the first direction. Each cover plate is fastened to one of the openings and welded to the housing.

[0020] Optionally, the shell is formed by bending the two ends of a long strip steel plate twice in opposite directions along its length, and then welding the two opposite sides of the long strip steel plate together to form a weld mark at the joint, thereby forming the cylindrical shell.

[0021] Optionally, both the housing and the cover are made of steel.

[0022] The beneficial effects of this invention are as follows:

[0023] This invention provides a battery cell, including a housing and a cover plate. At least one end of the housing has an opening, and the cover plate is disposed at the opening. The cover plate and the housing together form an accommodating space for mounting an electrode assembly. A seam is formed between the circumferential sidewall of the cover plate and the inner wall of the housing. Along a direction perpendicular to the circumferential sidewall of the cover plate, the housing and the cover plate are welded together using through-weld to form a first welded portion. The melting direction during the formation of the first welded portion is perpendicular to the circumferential sidewall of the cover plate. Along a direction perpendicular to the plane of the cover plate, the housing and the cover plate are welded together at the seam to form a second welded portion. The melting direction during the formation of the second welded portion is perpendicular to the plane of the cover plate, and the second welded portion is located on the end face of the cover plate away from the electrode assembly. When forming the second welded portion, the existing first welded portion at the seam can shield the laser generated during the formation of the second welded portion, preventing laser leakage into the accommodating space and burning the electrode assembly. Simultaneously employing two welding processes ensures high connection strength between the housing and the cover plate, stable and reliable welding quality, and avoids incomplete welding. Attached Figure Description

[0024] Figure 1 This is an exploded view of the battery cell provided in Embodiment 1 of the present invention;

[0025] Figure 2 This is a cross-sectional view of the battery cell provided in Embodiment 1 of the present invention;

[0026] Figure 3 yes Figure 2 A magnified view of a section at point I;

[0027] Figure 4 This is an exploded view of the battery cell provided in Embodiment 2 of the present invention.

[0028] In the picture:

[0029] 100, Shell; 110, Side wall; 111, Opening; 112, Weld mark; 200a, First cover plate; 200b, Second cover plate; 210, Positive electrode post; 220, Negative electrode post; 300, First welded part; 310, First molten area; 320, Second molten area; 400, Second welded part. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0031] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0034] Example 1

[0035] like Figures 1-3 As shown, this embodiment provides a battery cell, which includes a housing 100 and a cover plate. Both the housing 100 and the cover plate are made of steel. Steel has high hardness and mechanical strength, which can provide more reliable protection for the electrode assembly inside the battery cell. However, because of the high hardness and mechanical strength of steel, it is not easy to stamp a step on the housing 100 to support the cover plate. Therefore, the following installation scheme is adopted between the housing 100 and the cover plate in this embodiment.

[0036] Specifically, at least one end of the housing 100 has an opening 111, and a cover plate is disposed at the opening 111. The cover plate and the housing 100 together form an accommodating space for installing the electrode assembly. A joint is formed between the circumferential sidewall of the cover plate and the inner wall of the housing 100. The end face of the cover plate opposite to the electrode assembly is flush with the end face of the housing 100 along a first direction, which is a direction perpendicular to the plane where the cover plate is located. Figure 1The X-axis direction is shown in the diagram. When assembling the housing 100 and the cover plate, firstly, along a direction perpendicular to the circumferential sidewall of the cover plate, the housing 100 and the cover plate are welded to form a first welded portion 300. The first welded portion 300 is formed using a through weld, and the melting direction during its formation is perpendicular to the circumferential sidewall of the cover plate. The first welded portion 300 penetrates the housing 100 and is partially located on the circumferential sidewall of the cover plate. Thus, the housing 100 and the cover plate are pre-assembled as a single unit. The melting direction during the welding of the first welded portion 300 is perpendicular to the seam, preventing laser leakage into the accommodating space. Next, along a direction perpendicular to the plane of the cover plate, the housing 100 and the cover plate are welded at the seam to form a second welded portion 400. The second welded portion 400 is formed using a seam weld, and the melting direction during its formation is perpendicular to the plane of the cover plate. The second welded portion 400 is located on the end face of the cover plate away from the electrode assembly. Because of the presence of the first welded part 300, when the second welded part 400 is formed, the existing first welded part 300 at the joint can block the laser generated when the second welded part 400 is formed, preventing the laser from leaking into the accommodating space and burning the electrode assembly. At the same time, the use of two welding processes ensures a high connection strength between the housing 100 and the cover plate, stable and reliable welding quality, and avoids incomplete welding.

[0037] Optionally, in this embodiment, the shell 100 has openings 111 on both opposite sides along the first direction, and two cover plates are provided. Each cover plate is fastened to one opening 111 and welded to the shell 100 using the connection method described above. One cover plate is designated as the first cover plate 200a, and the other cover plate is designated as the second cover plate 200b. In this embodiment, the welding connection between the first cover plate 200a and the shell 100 is used as an example for explanation. Further, the shell 100 can be made using a long strip of steel plate. Specifically, after bending both ends of a long strip of steel plate towards each other along its length, the end of the long strip of steel plate is bent again along its length. Finally, the two opposite sides of the long strip of steel plate are welded together, forming a weld mark 112 at the joint, thereby forming a cylindrical shell 100. The cylindrical shell 100 includes four side walls 110, and the shell 100 has openings 111 at both ends along the first direction. The first direction is also the width direction of the elongated steel plate, which is perpendicular to its length direction. Optionally, in some embodiments, the weld mark 112 is located on the smaller side wall surface 110 of the housing 100.

[0038] See also Figure 3The wall thickness of the casing 100 is 'a', which is the thickness of the long strip steel plate. The value of 'a' ranges from 0.1mm to 0.3mm. For example, the value of 'a' can be 0.1mm, 0.2mm, or 0.3mm, etc. By controlling the value of 'a' within the above range, the casing 100 is guaranteed to have high mechanical strength, be able to resist a certain impact, and provide good protection for the electrode assembly. If the value of 'a' is too small, the wall thickness of the casing 100 is too thin, resulting in insufficient mechanical strength. On the one hand, the casing 100 is difficult to form during processing, and dimensional accuracy is difficult to guarantee; on the other hand, the casing 100 deforms severely when impacted, reducing its protective effect on the electrode assembly. If the value of 'a' is too large, the wall thickness of the casing 100 is too thick, resulting in excessive design redundancy, large material usage, high cost, and increased weight of the battery cell.

[0039] The thickness of the first cover plate 200a is b, and the value of b ranges from 0.5mm to 1.2mm. For example, the value of b can be 0.5mm, 0.8mm, 1.0mm, or 1.2mm, etc. By controlling the value of b within the above range, the first cover plate 200a is guaranteed to have high mechanical strength, be able to resist a certain impact, and provide good protection for the electrode assembly. If the value of b is too small, the first cover plate 200a is too thin, its mechanical strength is insufficient, it deforms severely when impacted, and its protection for the electrode assembly decreases. If the value of b is too large, the thickness of the first cover plate 200a is too large, resulting in excessive design redundancy, large material usage, high cost, and increased cell weight. Optionally, the thickness of the second cover plate 200b is equal to the thickness of the first cover plate 200a.

[0040] Furthermore, the portion of the first welded part 300 located on the first cover plate 200a is the first molten region 310, and the portion of the first welded part 300 located on the housing 100 is the second molten region 320. Along the first direction, the distance d between the side of the first molten region 310 near the accommodating space and the end face of the first cover plate 200a facing the accommodating space is 0 mm < d ≤ 0.3 mm. For example, the value of d can be 0.01 mm, 0.05 mm, 0.1 mm, 0.2 mm, or 0.3 mm, etc. By limiting the value of d to the above range, it is ensured that the first welded part 300 will not weld through the first cover plate 200a, preventing molten beads from falling and burning the electrode assembly during welding. The value of d should also not be too large; otherwise, the space left for the first welded part 300 and the second welded part 400 in the thickness direction (i.e., the first direction) of the first cover plate 200a will be insufficient, and the connection strength between the housing 100 and the first cover plate 200a will decrease.

[0041] Optionally, along the first direction, the distance between the side of the first molten region 310 facing away from the accommodating space and the end face of the first cover plate 200a facing away from the accommodating space is f, and the value of f is in the range of 0.1mm < f ≤ 2a. For example, the value of f can be 0.11mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, or 0.6mm, etc. It should be noted that the value of f should not be too large, otherwise the distance between the first welded part 300 and the end face of the first cover plate 200a facing away from the electrode group will be too far, and the first welded part 300 will easily cause the shell 100 to deform after welding, the joint between the shell 100 and the first cover plate 200a will be too large, and ultimately the second welded part 400 will have a poor weld.

[0042] Furthermore, along the first direction, the penetration depth of the second weld 400 on the first cover plate 200a and the housing 100 is e, where e ranges from 0.1mm to e < f. For example, the value of e can be 0.1mm, 0.15mm, 0.25mm, 0.35mm, 0.45mm, or 0.55mm, etc. By limiting the value of e to the above range, a reliable connection between the housing 100 and the first cover plate 200a can be guaranteed, resulting in good weld quality. Otherwise, if the value of e is too small, the molten pool formed on the housing 100 and the first cover plate 200a during welding will be small, resulting in insufficient weld strength between the housing 100 and the first cover plate 200a and reduced reliability. If the value of e is too large, the welding power required during welding will be large, which may lead to the risk of hole bursting.

[0043] Along the direction perpendicular to the circumferential sidewall of the first cover plate 200a (i.e., the second direction, such as...) Figure 2 As shown on the Y-axis (in the diagram), the penetration depth of the first molten region 310 is c, and the value of c ranges from 0.1 mm to 0.5 mm. For example, the value of c can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm, etc. By limiting the value of c to the above range, a reliable connection between the shell 100 and the first cover plate 200a can be guaranteed, resulting in good welding quality. Otherwise, if the value of c is too small, the molten pool formed on the shell 100 and the first cover plate 200a during welding will be small, the welding strength between the shell 100 and the first cover plate 200a will be insufficient, and the reliability will be reduced. If the value of c is too large, the welding power required during welding will be large, and the risk of pore breakage will easily occur.

[0044] Furthermore, the battery cell also includes a positive terminal 210 and a negative terminal 220. Both the positive terminal 210 and the negative terminal 220 are disposed on the first cover plate 200a, and the positive terminal 210 and the negative terminal 220 are respectively placed on both sides of the first cover plate 200a along the second direction, and the positive terminal 210 and the negative terminal 220 are symmetrically arranged about the center of the first cover plate 200a.

[0045] The following uses samples from specific implementation cases to verify the relevant dimensional design of the above-mentioned battery cells. See Table 1 for details.

[0046] Table 1

[0047]

[0048] As can be seen from the above results, the values ​​of parameters a and f in Examples 1 to 6 all meet their corresponding size limitations. The welding quality of the first welded part 300 and the second welded part 400 between the shell 100 and the first cover plate 200a is good, and there are no welding defects such as false welds or bursts. The sealing effect of the joint between the shell 100 and the first cover plate 200a is good. After long-term use, it can still pass the helium test, with a long service life, high reliability, and good product quality.

[0049] In Comparative Examples 1 and 2, the value of parameter f is greater than 2a, exceeding the maximum value of its range 0.1mm < f ≤ 2a. At this time, the first welded part 300 is too far from the end face of the first cover plate 200a on the side opposite to the electrode assembly. Welding the first welded part 300 easily leads to deformation of the housing 100, resulting in an excessively large seam between the housing 100 and the first cover plate 200a, ultimately causing a weak weld on the second welded part 400. The connection strength between the housing 100 and the first cover plate 200a decreases, and the sealing effect at the seam between them is poor. After prolonged use, air leakage occurs at the seam, failing helium testing and posing a risk of airtightness failure, resulting in a short service life and product defects.

[0050] Taking all factors into consideration, when the dimensions of cell a and f both meet the above-mentioned dimensional requirements, it can be ensured that the connection strength between the housing 100 and the first cover plate 200a is high, the sealing performance at the connection between the housing 100 and the first cover plate 200a is good, and it can be used for a long time without leakage, with high reliability and good quality of cell products.

[0051] Example 2

[0052] This embodiment provides a battery cell that differs from the battery cell in Embodiment 1 in that the positions of the positive terminal 210 and the negative terminal 220 on the cover plate of the battery cell in this embodiment are different.

[0053] See Figure 4 In this embodiment, the battery cell includes a housing 100 and two cover plates, with the housing 100 along a first direction ( Figure 4 Openings 111 are provided on both sides of the housing 100 in the X-axis direction shown in the diagram. Each cover plate is fastened to one opening 111 and welded to the housing 100. One cover plate is designated as the first cover plate 200a, and the other cover plate is designated as the second cover plate 200b. The positive electrode post 210 can be mounted on the first cover plate 200a along the second direction (…). Figure 4 The positive terminal 210 can be eccentrically positioned on the first cover plate 200a along the second direction (as shown in the Y-axis direction). Alternatively, the negative terminal 220 can also be positioned at the middle of the second cover plate 200a along the second direction.

[0054] The remaining structures in this embodiment are the same as those in Embodiment 1, and will not be described in detail here.

[0055] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A battery cell, characterized in that, include: A housing, wherein at least one end of the housing is provided with an opening; A cover plate is disposed at the opening. The cover plate and the housing together form an accommodating space for installing the electrode assembly. A joint is formed between the circumferential sidewall of the cover plate and the inner wall of the housing. The end face of the cover plate facing away from the electrode assembly is flush with the end face of the housing along a first direction, which is a direction perpendicular to the plane where the cover plate is located. Wherein, along the direction perpendicular to the circumferential sidewall of the cover plate, the housing and the cover plate are welded together by through-welding to form a first welded part, and the melting direction of the first welded part is perpendicular to the circumferential sidewall of the cover plate; along the direction perpendicular to the plane of the cover plate, the housing and the cover plate are welded together by seam welding at the joint to form a second welded part, and the melting direction of the second welded part is perpendicular to the plane of the cover plate, and the second welded part is located on the end face of the cover plate away from the electrode assembly; The portion of the first weld located on the cover plate constitutes the first molten zone; Along the first direction, the distance between the side of the first molten region near the accommodating space and the end face of the cover plate facing the accommodating space is d; The range of values ​​for d is: 0 mm < d ≤ 0.3 mm; Along the direction perpendicular to the circumferential sidewall of the cover plate, the melting depth of the first molten region is c; The value range of c is: 0.1mm≤c≤0.5mm.

2. The battery cell according to claim 1, characterized in that, The wall thickness of the shell is a; The range of values ​​for a is: 0.1mm ≤ a ≤ 0.3mm.

3. The battery cell according to claim 2, characterized in that, The thickness of the cover plate is b; The value of b is in the range of 0.5mm ≤ b ≤ 1.2mm.

4. The battery cell according to claim 1, characterized in that, Along the first direction, the distance between the side of the first molten region away from the accommodating space and the end face of the cover plate away from the accommodating space is f; The range of values ​​for f is: 0.1mm < f ≤ 2a.

5. The battery cell according to claim 4, characterized in that, Along the first direction, the penetration depth of the second weld on the cover plate and the housing is e; The range of values ​​for e is: 0.1mm≤e<f.

6. The battery cell according to claim 1, characterized in that, The cover plate is provided in two parts, and the shell has openings on both sides of the opposite side along the first direction. Each cover plate is fastened to one of the openings and welded to the shell.

7. The battery cell according to claim 6, characterized in that, The shell is formed by bending the two ends of a long strip of steel plate twice in opposite directions along its length, and then welding the two opposite sides of the long strip of steel plate together to form a weld mark at the joint, thus forming the cylindrical shell.

8. The battery cell according to claim 1, characterized in that, Both the housing and the cover plate are made of steel.

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